RESUMEN
The aim of this study was to investigate the effects of different types of exercise on intestinal mechanical barrier and related regulatory factors in mice with type 2 diabetes mellitus (T2DM). The model was established by high-fat diet feeding and intraperitoneal injection of streptozocin (STZ). The mice were divided into control group, model group (free exercise), resistance exercise group (tail load-bearing ladder climbing, 5 times a week), aerobic exercise group (non-load-bearing platform running, 5 times a week at a speed of 10-15 m/min), and combined exercise group (aerobic exercise was performed on the first, third and fifth days of each week, and resistance exercise on the second and fourth days of each week). After 8 weeks of intervention, the serum lipid levels and inflammatory cytokines were measured by corresponding kits. The pathological changes of ileum were detected by HE and PAS staining. The mRNA and protein expression levels of tight junction-related proteins were detected by real-time qPCR and Western blot, respectively. Moreover, the protein expression levels of hypoxia inducible factor-1α (HIF-1α) and myosin light chain kinase (MLCK) were detected by Western blot. The results showed that all three types of exercise decreased blood glucose and body weight compared to the model group. Aerobic exercise and combined exercise decreased serum lipid (triglycerides and total cholesterol) levels, up-regulated the expression levels of ileal tight junction-related proteins and HIF-1α, improved the intestinal alkaline phosphatase (AKP) activity, reduced serum lipopolysaccharide (LPS), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and diamine oxidase (DAO) levels, and down-regulated MLCK protein expression level. These results suggest that all three types of exercise can reduce blood glucose and body weight of T2DM mice, and aerobic exercise and combined exercise can restore the damaged intestinal mechanical barrier by a mechanism involving HIF-1α-MLCK pathway.